The present invention relates to automated welding of the open end of a nuclear fuel pin cladding assembly. It comprises a welding fixture for coaxially positioning the cladding, an inserted end cap, and a surrounding driver sleeve for closure of the cladding end by pulsed magnetic welding.
This disclosure relates specifically to an improvement in the positioning of a fuel pin end cap for closure of the cladding in a fuel pin by pulsed magnetic welding techniques. In such applications, the cladding is welded about the circumference of an inserted end cap that has a tapered transition zone between a cylindrical section having an exterior diameter substantially equal to the cladding interior diameter, and an outwardly extending stem of reduced diameter. A sleeve of magnetic material is collapsed about the open end of the cladding to weld it about the tapered zone.
The design of the present welding fixture has been directed to two problems encountered during adaptation of pulsed welding techniques to the closure of fuel pin assemblies. First is the requirement that the end cap, driver sleeve and open end of the cladding be accurately arranged in coaxial positions for automated welding purposes. Second, provision must be made to entrap ejected contaminant particles that might be forced from the open end of the length of cladding as it is progressively collapsed along the tapered transition zone.